The inventors of the present invention have made a prior art search on a flocked metal plate which is made by forming a flocked layer made of short fiber bundles on a synthetic resin adhesive layer formed on a surface of a metal plate with a high flocking density and is used as a construction material. As a result of the prior art search, there has been disclosed a construction material which is manufactured such that a steel sheet is used as a substrate, rustproofing is applied to the substrate, a synthetic resin adhesive layer which is a short-fiber implanting layer is directly formed on the substrate using an specially blended synthetic resin adhesive, and non-metal fiber bundles are implanted in the synthetic resin adhesive layer thus forming a flocked layer (see patent document 1, for example). Further, there has been also disclosed a construction material which is manufactured such that a steel sheet is used as a substrate, chromate treatment or the like is applied to the substrate, a synthetic resin adhesive layer which is a short-fiber implanting layer is formed on the substrate using an specially blended synthetic resin adhesive while interposing a primer layer on a surface of the steel sheet treated with chromate or the like without directly forming a synthetic resin adhesive layer which is the short-fiber implanting layer on the steel sheet, and short fiber bundles are implanted in the synthetic resin adhesive layer with high flocking density thus forming a flocked layer (see patent document 2, for example).
In patent document 1, in applying the synthetic resin adhesive to the substrate, the synthetic resin adhesive is applied by spray coating or the like and hence, viscosity of the synthetic resin adhesive layer which constitutes the short-fiber implanting layer is low whereby there arises a drawback that an adhesive strength between a surface of a metal plate and the synthetic resin adhesive layer constituting the short-fiber implanting layer and an adhesive strength between the synthetic resin adhesive layer and short fibers which are implanted in the synthetic resin adhesive layer deteriorate. In Patent Document 2, a primer layer is required and necessitates primer coating and a drying apparatus therefor, thereby a manufacturing cost is increased.
The inventors of the present invention previously filed patent applications (see patent documents 3 and 4, for example) on a technique which differs from the technique disclosed in the publication referred to as patent document 2. That is, the inventors of the present invention previously filed the patent applications on a flocked steel sheet which is manufactured by directly forming a synthetic resin adhesive layer which constitutes a short-fiber implanting layer on a surface treated steel sheet without interposing a primer layer and by implanting short fibers on the synthetic resin adhesive layer as short fiber bundles at high density and which is used as a construction material.
Here, in using the flocked metal plate which constitutes the construction material as a metal-made roof or eaves of a building, a surface of the flocked metal plate on which a flocked layer is not formed is placed on an outer side of the roof or eaves (forming an upper surface of the roof or eaves), and a surface of the flocked metal plate on which the flocked layer is formed is placed on an inner side of the roof or eaves (forming a lower surface of the roof or eaves). When a metal roof or eave is made of a flocked metal plate composed of a construction material produced by employing the prior art stated above, the flocked metal plate composed of the construction material as a metal roof or eave material has dew formed on its inner and outer surfaces by natural phenomena caused by changes in weather, especially a phenomenon of radiation cooling occurring at the dawn of a fine day in winter (a phenomenon producing a temperature difference of 5° C. to 6° C. between the environment and the flocked metal plate). The flocked layer of the flocked metal plate made as a construction material employing the prior art stated above is a flocked layer formed by forming a synthetic resin adhesive layer as a short fiber implanting layer from a synthetic resin adhesive prepared without taking hydrophilicity into account, and employing short fibers prepared without taking hydrophilicity into account to implant bundles of short fibers in that layer.
That is, the flocked metal plate which is manufactured by the conventional technique has not paid any consideration with respect to a means which can prevent falling of dews which are generated in the synthetic resin adhesive layer constituting the short-fiber implanting layer and the flocked layer which is formed of short fibers which are implanted on the synthetic resin adhesive layer as short fiber bundles at high density. Accordingly, when a roof is constructed using the flocked metal plate manufactured by the prior art, dews which are generated in the flocked layer of the flocked metal plate fall as drops from tip ends of the short fiber bundles thus causing following drawbacks. That is, people standing or sitting below the roof or products placed below the roof become wet with water, the dews stains clothing of a person, or the dews spoil a commercial value of products. Particularly, even when the product is not completely wet with water but absorbs moisture therein due to slight leaking of water from the roof, this may also cause drawbacks such as deterioration of the commercial value of the product.
Further, when rainwater or snowmelt infiltrates into the flocked layer, a phenomenon similar to the above-mentioned phenomenon occurs.
Still further, to consider a duct for air-conditioning system which is manufactured using a conventional flocked metal plate, the dew condensation occurs on a flocked layer of the flocked metal plate which constitutes an outer surface of the duct at the time of starting the use of the air-conditioning system. When dews fall as water droplets, the dews cause a drawback that a clothing of a person below the air-conditioning system is stained with water droplets, or merchandise below the air-conditioning system or the like are also stained with water droplets leading to the degradation of a commercial value of the products.
The inventors of the present invention have come up with an idea that, to prevent dews generated in the flocked layer of the flocked metal plate or rainwater or snowmelt soaked into the flocked layer from falling from tip ends of the short fiber bundles which form the flocked layer, it is necessary to impart hydrophilicity to the synthetic resin adhesive layer which constitutes the short-fiber implanting layer and the flocked layer which is formed on the synthetic resin adhesive layer as short fiber bundles so that the synthetic resin adhesive layer and the flocked layer exhibit water retention property. The inventors of the present invention also have come up with an idea that, to realize the above-mentioned constitution, it is necessary to apply particular improvements to the synthetic resin adhesive layer which is the short-fiber implanting layer constituting the flocked layer formed on the flocked metal plate, short fibers which are implanted in the synthetic resin adhesive layer, a flocked state of the short fiber bundles formed of short fibers and the like.
That is, the inventors of the prevent invention have considered that, with respect to the flocked layer, besides applying the particular improvements to the synthetic resin adhesive layer which is the short-fiber implanting layer for forming the flocked layer and the short fibers which are implanted in the synthetic resin adhesive layer, it is necessary to form the short fiber bundles in a flocked state which allows the flocked layer to exhibit a capillary phenomenon acting in the flocked layer at maximum.
Patent document 5 discloses a technique in which two electrodes consisting of a first electrode and a second electrode are arranged in an electrostatic flocking chamber along a feeding path of a work to be flocked, high-voltage static electricity is applied to the first electrode and high-voltage static electricity which is lower than the high-voltage static electricity applied to the first electrode is applied to the second electrode thus enhancing the flocking density of fibers flocked on the work which passes the electrostatic flocking chamber. However, this document fails to disclose a technique of the present invention which allows a flocked layer of a flocked metal plate to exhibit hydrophilicity, water retention property, and water absorbing property using a work formed of an elongated metal plate which passes an electrostatic flocking chamber.
Further, in manufacturing the flocked metal plate, the inventors of the present invention also have made a finding that the adjustment of drying temperature after flocking the short fibers on the synthetic resin adhesive layer which is the short-fiber implanting layer formed on the metal plate influences water retention property, water absorbing property or hydrophobicity of the flocked layer formed on the flocked metal plate.
Following is the information on prior-art documents relating to the present invention.    Patent document 1: JP-A-5-138813    Patent document 2: JP-B-62-27864    Patent document 3: Japanese Patent No. 2956033    Patent document 4: Japanese Patent No. 3001451    Patent document 5: JP-A-2001-46923